0. 保存Bitmap到指定路径
参考网址：android保存bitmap到指定路径
1. 加载资源图片
把PNG图片拖到工程中res中的drawable-hdpi中; （JPG需要转换格式到PNG）
InputStream is = getResources().openRawResource(R.drawable.pic_name); //图片名为pic_name.png
Bitmap bitmap = BitmapFactory.decodeStream(is);
ImageView.setImageBitmap(bitmap);
2. 加载系统图库图片
参考网址： Android 如何从系统图库中选择图片
@Override
public void onClick(View view) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/*");
//intent.putExtra("crop", true); //裁剪图片
intent.putExtra("return-data", true);
startActivityForResult(intent, RESULT_LOAD_IMAGE);
}
...
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) {
Uri pic = data.getData();
Log.d("onActivityResult", "chosen pic: " + pic.getPath());
InputStream input = null;
try {
input = this.getActivity().getContentResolver().openInputStream(pic);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
if(input != null) {
imageView.setImageBitmap(BitmapFactory.decodeStream(input));
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
}
}
}
3. bitmap转YUV
参考网址：android bitmap转YUV
4. bitmap图片翻转(镜像)
垂直对称(y轴对称)：
Matrix matrix = new Matrix();
float matrixValues[] = {-1f, 0f, 0f, 0f, 1f, 0f, 0f, 0f, 1f};
matrix.setValues(matrixValues);
//matrix.postTranslate(image.width, 0); //表示将图片左右倒置
matrix.postTranslate(width*2, 0);
canvas.drawBitmap(bitmap, matrix, paint);
参考网址：Android图片旋转,缩放,位移,倾斜,对称完整示例(二)——Bitmap.createBitmap()和Matrix
5. bitmap图片缩放
Matrix matrix = new Matrix();
matrix.postScale(float sx, float sy);
canvas.drawBitmap(bitmap, matrix, paint);
6. argb数据生成Bitmap
Bitmap bitmap = Bitmap.createBitmap(bytes, width, height, Config.ARGB_8888);
7. 加载YUV Image
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21, width, height, null);
yuvImage.compressToJpeg(new Rect(0, 0, width, height), 50, out);
byte[] imageBytes = out.toByteArray();
Bitmap image = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.length);
imageview.setImageBitmap(image);
参考网址：Displaying YUV Image in Android
or:
yuv420->rgb565/argb8888->bitmap对象->bmp图片
8. Bitmap图片旋转
/**
* 读取图片的旋转的角度
*
* @param path 图片绝对路径
*
* @return 图片的旋转角度
*/
private int getBitmapDegree(String path) {
int degree = 0;
try {
// 从指定路径下读取图片，并获取其EXIF信息
ExifInterface exifInterface = new ExifInterface(path);
// 获取图片的旋转信息
int orientation = exifInterface.getAttributeInt(ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_NORMAL);
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
degree = 90;
break;
case ExifInterface.ORIENTATION_ROTATE_180:
degree = 180;
break;
case ExifInterface.ORIENTATION_ROTATE_270:
degree = 270;
break;
}
} catch (IOException e) {
e.printStackTrace();
}
return degree;
}
/**
* 将图片按照某个角度进行旋转
*
* @param bm 需要旋转的图片
*
* @param degree 旋转角度
*
* @return 旋转后的图片
*/
public static Bitmap rotateBitmapByDegree(Bitmap bm, int degree) {
Bitmap returnBm = null;
// 根据旋转角度，生成旋转矩阵
Matrix matrix = new Matrix();
matrix.postRotate(degree);
try {
// 将原始图片按照旋转矩阵进行旋转，并得到新的图片
returnBm = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), matrix, true);
} catch (OutOfMemoryError e) {
}
if (returnBm == null) {
returnBm = bm;
}
if (bm != returnBm) {
bm.recycle();
}
return returnBm;
}
参考网址：
9. Bitmap压缩
方法一、采样率压缩
SDcard图片加载并压缩(decodeFile)，参考网址：Android手机拍照上传被旋转90度的处理方法-getimage代码，代码如下：
public static Bitmap getImage(String srcPath) {
BitmapFactory.Options newOpts = new BitmapFactory.Options();
//开始读入图片，此时把options.inJustDecodeBounds 设回true了
newOpts.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(srcPath,newOpts);//此时返回bitmap为空
int w = newOpts.outWidth; //图片宽
int h = newOpts.outHeight;//图片高
//设置目标宽高。由于图片采用缩放比压缩，压缩后图片尺寸为近似目标宽高
float ww = 480f;
float hh = 800f;
//缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可
int be = 1; //be=1表示不缩放
#if 0
if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放
be = (int) (w / ww);
} else if (w < h && h > hh) {//如果高度高的话根据高度固定大小缩放
be = (int) (h / hh);
}
if (be <= 0) {
be = 1;
}
#else // 缩放比为1, 2, 4, 8...
if (w > h && w > ww) {
be = Math.round(w / ww);
} else if (w < h && h > hh) {
be = Math.round(h / hh);
}
if (be <= 0) {
be = 1;
} else if (be > 1) {
double x = Math.log10(be) / Math.log10(2);
be = (int) Math.pow(2, Math.ceil(x));
}
#endif
newOpts.inSampleSize = be;//设置缩放比例
newOpts.inJustDecodeBounds = false;
//重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了
return BitmapFactory.decodeFile(srcPath, newOpts);
}
图库图片加载并压缩(decodeStream)，参考网址：decodeStream returns null(second invoke)，代码如下：
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) {
Uri uri = data.getData();
// String srcPath = uri.getPath();
Bitmap bmp = getImage(uri);
}
}
public static Bitmap getImage(Uri uri) {
BitmapFactory.Options newOpts = new BitmapFactory.Options();
newOpts.inJustDecodeBounds = true;
InputStream is = null;
try {
is = this.getActivity().getContentResolver().openInputStream(uri);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
BitmapFactory.decodeStream(is, null, newOpts);
int w = newOpts.outWidth;
int h = newOpts.outHeight;
float ww = EXPECTED_WIDTH; // 目标(期望)宽度
float hh = EXPECTED_HEIGHT;// 目标(期望)高度
int be = 1;
if (w > h && w > ww) {
be = Math.round(w / ww);
} else if (w < h && h > hh) {
be = Math.round(h / hh);
}
if (be <= 0) {
be = 1;
} else if (be > 1) {
double x = Math.log10(be) / Math.log10(2);
be = (int) Math.pow(2, Math.ceil(x));
}
newOpts.inSampleSize = be;
newOpts.inJustDecodeBounds = false;
InputStream isNew = null;
try {
isNew = this.getActivity().getContentResolver().openInputStream(uri);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return BitmapFactory.decodeStream(isNew, null, newOpts);
}
方法二、缩放压缩(postScale)
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) {
Uri uri = data.getData();
InputStream is = null;
try {
is = this.getActivity().getContentResolver().openInputStream(uri);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Bitmap bmp = BitmapFactory.decodeStream(is);
int w = bmp.getWidth();
int h = bmp.getHeight();
float ww = EXPECTED_WIDTH; // 目标(期望)宽度
float hh = EXPECTED_HEIGHT;// 目标(期望)高度
Matrix matrix = new Matrix();
matrix.postScale(ww/w, hh/h);
Bitmap bitmap = Bitmap.createBitmap(bmp, 0, 0,
bmp.getWidth(), bmp.getHeight(), matrix, true);
}
}
10. Bitmap保存.bmp格式
参考网址：
11. Bitmap转yuv420sp(NV21)
public static byte[] getYUV420sp(int inputWidth, int inputHeight, Bitmap scaled) {
int[] argb = new int[inputWidth * inputHeight];
scaled.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);
byte[] yuv = new byte[inputWidth * inputHeight * 3 / 2];
encodeYUV420SP(yuv, argb, inputWidth, inputHeight);
//scaled.recycle();
return yuv;
}
private static void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {
int Y, U, V;
int yIndex = 0;
int R, G, B;
int argbIndex = 0;
for (int j = 0; j < height; j++) {
for (int i = 0; i < width; i++) {
//int A = (argb[argbIndex] & 0xff000000) >> 24;
R = (argb[argbIndex] & 0xff0000) >> 16;
G = (argb[argbIndex] & 0xff00) >> 8;
B = (argb[argbIndex] & 0xff);
argbIndex++;
// well known RGB to YUV algorithm
Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;
Y = Math.max(0, Math.min(Y, 255));
U = Math.max(0, Math.min(U, 255));
V = Math.max(0, Math.min(V, 255));
// ---Y---
yuv420sp[yIndex++] = (byte) Y;
}
}
}
12. 解决Android加载图片导致内存溢出
/*
* scalSize: 缩小比例
* eg,. scalSize = 10, width and height设为原来的1/10
*/
private Bitmap loadBitmap(String path, int scalSize) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inSampleSize = scalSize;
Bitmap bmp = BitmapFactory.decodeFile(path, options);
return bmp;
}
参考网址： Android加载图片导致内存溢出（Out of Memory异常）
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